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Chapter 24

Software Environment

281

20695H/0—March 1998

AMD-K6® Processor Data Sheet

Preliminary Information

Software Environment

This chapter briefly describes the AMD-K6 Model-Specific

Registers (MSRs) and x86 instructions supported by the

AMD-K6 processor Model 7 that are not supported by the

AMD-K6 processor Model 6.

For an overview of the AMD-K6 processor’s x86 software

environment and a description of the remaining data types,

registers, operating modes, interrupts, and instructions

support e d b y the AMD -K 6 ar c h itect u r e and design

implementation, see Chapter 3, “Software Environment” on

page 21.

24.1

Registers

The AMD-K6 processor contains all the registers defined by the

x86 architecture, including ge ne ral-purpose , segm ent,

floating-point, MMX, EFLAGS, control, task, debug, test, and

descriptor/memory-management registers.

This section provides information on the Model-Specific

Registers (MSRs) supported by the AMD-K6 processor Model 7

that are not supported by the AMD-K6 processor Model 6. For

information about the remaining AMD-K6 registers, see

Chapter 3, “Software Environment” on page 21.

Note: Areas of the register designated as Reserved should not be

modified by software.

Model-Specific

Registers (MSR)

The AMD-K6 processor Model 7 supports two additional MSRs

as compared to the AMD-K6 processor Model 6. The value in the

ECX register selects the MSR to be addressed by the RDMSR

and WRMSR instructions. The values in EAX and EDX are used

as inputs and outputs by the RDMSR and WRMSR instructions.

Table 59 lists the new MSRs and the corresponding value of the

ECX register. Figures 102 and 103 show the MSR formats.

AMD-K6 Datasheet(PDF) 299 Page - Advanced Micro Devices